JP2833678B2 - Electrophotographic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device having a first to a third fixing roller, a pressing portion of a first and a second fixing roller, and a pressing portion of a second and a third fixing roller. And an electrophotographic apparatus in which a fixing unit is formed.

[0002]

2. Description of the Related Art A copying machine as an electrophotographic apparatus generally includes a fixing device having a pair of heat rollers, an electrostatic latent image corresponding to a document is formed on a photosensitive member, and a toner image is formed by a developer. After being visualized as, the toner image is transferred onto the sheet, and the sheet is heated and melted and fixed by passing the sheet between the two heat rollers in the fixing device. .

[0003] Conventionally, for example, Japanese Patent Laid-Open No. 51-98
No. 036, the fixing device
A first fixing unit is formed at a pressure contact portion between the upper heat roller and the middle heat roller, and a middle fixing roller is formed at a pressure contact portion between the middle heat roller and the lower heat roller. There has been proposed an apparatus in which a second fixing unit is formed, and a sheet conveying device for conveying a sheet to the first and second fixing units is moved according to a fixing unit to be used.

According to such a configuration, by appropriately selecting the material of the upper, middle, and lower heat rollers, compared to a case where only a pair of heat rollers are provided in the fixing device, paper, paper, It can handle sheets made of various materials such as labels, mylar, and polycarbonate. Then, in the above-mentioned sheet conveying apparatus, the first
The movement to the upper position where the sheet can be conveyed to the fixing unit and the lower position where the sheet can be conveyed to the second fixing unit is performed by rotating the sheet conveying device with its solenoid around the paper input side end. It has become.

However, the solenoid for driving the sheet conveying device between the upper position and the lower position as described above is inevitably large and expensive, which leads to an increase in the size and cost of the device. Have a point.

Accordingly, the present inventors have previously provided a fixing device having three heat rollers, and a sheet conveying device for conveying a sheet to the fixing device, using a sheet conveying driving source as a driving source. And Japanese Patent Application No. 4-55325 (hereinafter referred to as Japanese Patent Application No. 4-55325) has proposed a moving part position moving means for moving a sheet conveying moving part of a sheet conveying apparatus to an upper position and a lower position.
No.). As shown in FIG. 6, a suction unit 500 serving as a sheet conveying device that conveys a sheet on which a toner image corresponding to a document is transferred to a fixing device includes two conveying belts 501 and 501 that are driven on a paper input side. The sheet is supported by a shaft 502 and a driven shaft 503 on the paper output side. When power from a sheet conveyance drive source (not shown) is transmitted to the drive shaft 502, the sheet is orbited in the direction A, which is the sheet conveyance direction. It has become. The driven shaft 503 is rotatably attached to the paper output side end of the suction plate 506,
On its lower surface, a suction case 507 having a suction fan (not shown) is provided. The transfer belt 5
A sheet transporting / moving unit 521 is configured by a part that moves up and down such as 01 · 501 and the suction plate 506.

The rotation of the drive shaft 502 by the power of the sheet conveying drive source is controlled by the sprocket 513, the timing belt 514, the sprocket 512, and the idle shaft 51.
1, the gear 515, the spring clutch 516, and the like, are transmitted to the camshaft 509, and the rotation of the camshaft 509 causes the eccentric cams 510, 510, which are in contact with the lower surface of the suction case 507, to rotate. , The sheet transport moving unit 521 moves up and down.

When the operating portion 517a of the solenoid 517 is engaged with the locking projection 516a of the spring clutch 516, the transmission of power to the camshaft 509 is cut off, and the sheet transporting portion 521 is moved upward. Alternatively, it is held at a lower position. Further, an upper position sensor and a lower position sensor (not shown) are provided to detect the position of the sheet transport moving unit 521, and the vertical movement of the sheet transport moving unit 521 is controlled according to a detection signal from these position sensors. It is supposed to be.

Therefore, with the above configuration, a dedicated driving source for driving the sheet conveying / moving unit 521 becomes unnecessary, and the size and cost of the apparatus can be reduced.

[0010]

However, in the above configuration, although a driving source dedicated to the sheet transport moving unit 521 is not necessary, the power from the sheet transport driving unit is transmitted, and the sheet transport moving unit 521 is moved up and down. In order to move, the sprocket 513, the timing belt 514, the sprocket 512, the idle shaft 511, the gear 515, the spring clutch 516, the cam shaft 509, the eccentric cams 510 and 50.5.
10 and a moving mechanism including the solenoid 517, an upper position sensor and a lower position sensor for controlling the movement of the sheet conveying moving unit 521, and the like.

Further, for example, upper and lower heat rollers are provided so as to be detachable from the middle heat roller, and when the upper heat roller is pressed against the middle heat roller to form the first fixing section, When separating the lower heat roller and pressing the lower heat roller against the middle heat roller to form the second fixing section, when separating the upper heat roller from the middle heat roller, move the upper and lower heat rollers up and down. A moving mechanism for moving is also required. As described above, when the upper and lower heat rollers and the sheet conveying / moving unit are driven by different moving mechanisms, the number of components increases, so that cost reduction cannot be achieved, and the first or second fixing unit is not required. In order to move the sheet conveying moving unit of the sheet conveying device to the upper position or the lower position in accordance with the movement of the upper and lower heat rollers for forming the unit, the timing for operating both moving mechanisms must be controlled. If the position of the upper and lower heat rollers does not match the position of the sheet transporting unit due to a malfunction for some reason, a paper jam may occur.

[0012]

According to the present invention, there is provided an electrophotographic apparatus comprising:
A first fixing portion is formed at a pressure contact portion between the first fixing roller and the second fixing roller, and a second fixing portion is formed at a pressure contact portion between the second fixing roller and the third fixing roller. Is formed, and a fixing device for feeding the sheet conveyed to each fixing unit in the discharge direction by rotation of the fixing roller, a first fixing unit sheet conveying position for conveying the sheet on which the toner image has been transferred to the first fixing unit, and a first fixing unit. (2) an electrophotographic apparatus comprising: a sheet conveying device having a sheet conveying moving unit movably provided at a second fixing unit sheet conveying position for conveying to a fixing unit, wherein the first fixing roller is rotatably supported. , 2nd fixing low
Direction and separation of the first fixing roller against the roller
A first support member movable in a direction to be
Roller is rotatably supported, and the third fixing roller is fixed to the second fixing roller.
Move in the direction of pressing and separating the application roller
A possible second support member, a rotatable rotating member,
Is provided on the rotating member of the
A first cam for moving the first and second support members;
The rotating member is provided on the rotating member.
Mover having a second cam for moving the sheet transport moving section
A step, and the moving means moves with the rotation of the rotating member.
By the first and second cam rotating Te, the first fixing roller is pressed against the second fixing roller, and the third fixing roller with it is separated from the second fixing roller, the Sea <br/> preparative conveying movement Unit to the first fixing unit sheet transport position
A first state, to move the third fixing roller is pressed against the second fixing roller, and the first fixing roller with is separated from the second fixing roller, the sheet transport moving portion to the second fixing portion sheet transport position Forming a second state.
It is characterized in that that.

[0013]

According to the above arrangement, the first and third fixing rollers in the fixing device and the sheet transporting section in the sheet transporting device are linked by the same moving means. Therefore, the number of components such as the moving mechanism and the sensor can be reduced as compared with the case where the first and third fixing rollers and the sheet conveying moving unit are driven by different moving mechanisms, respectively, and thus cost reduction is realized. it can.

Further, since the first and third fixing rollers and the sheet transporting and moving unit are always linked, there is no need to control the timing of the movement, and a malfunction such that their positional relationships do not match. Since the possibility of occurrence can be avoided, the occurrence of paper jam can be reduced.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. A full-color copying machine as an electrophotographic apparatus in the present embodiment (hereinafter simply referred to as a copying machine)
As shown in FIG. 2, an original mounting table 3 made of hard transparent glass is provided on the upper surface of the copying machine main body 1, and an exposure optical system 4 is provided below the original mounting table 3. The exposure optical system unit 4 includes a lamp unit 5 that scans a document (not shown) placed on the document table 3 while irradiating light, and a plurality of light units that guide reflected light from the document to the photoconductor 8. Reflecting mirror 6 ...
A lens unit 7 disposed in the optical path of the reflected light.

A charging charger 9 for charging the surface of the photoreceptor 8 to a predetermined potential is provided on the outer periphery of the photoreceptor 8. Toward, an inter-image eraser (not shown), a black developing tank 10, a yellow developing tank 11, a magenta developing tank 12, a cyan developing tank 13, and an intermediate transfer device 1
4, a cleaning device 15, and a static elimination device 16 are arranged in this order.

The above-mentioned intermediate transfer device 14 is used to transfer the transfer belt 1
7, rollers 18 and 19 for supporting the transfer belt 17
20, the transfer belt 17 is brought into pressure contact with the photoconductor 8,
A first transfer roller 21 for transferring the toner image formed on the surface to the transfer belt 17, and a second transfer for pressing the toner image on the surface of the transfer belt 17 onto the sheet when the toner image is transferred to the sheet by pressing the roller 20. A roller 22 and a cleaning device 23 for removing residual toner on the surface of the transfer belt 17 are provided.

On the paper supply side of the intermediate transfer device 14, a registration roller 24, a paper supply cassette 25, and a paper supply tray 26 for supplying paper to the intermediate transfer device 14 at a predetermined timing are provided. In the vicinity of the cassette 25 and the paper feed tray 26, a paper feed roller 27, a transport roller 28, and the like are provided.

In the paper output direction from the intermediate transfer device 14, a suction unit 100 as a sheet transport device for transporting the paper, a fixing device 200 for heating and melting the toner and fixing it on the sheet, a paper discharge roller 30, and a paper discharge roller Paper tray 3
1 is provided.

In the fixing device 200, as shown in FIG.
An upper heat roller 201 as a first fixing roller;
A middle heat roller 202 as a fixing roller and a lower heat roller 203 as a third fixing roller are provided in parallel in the vertical direction. In the present embodiment, the fixing at the time of full-color copying is performed by the upper fixing section as the first fixing section formed at the press contact portion between the upper heat roller 201 and the middle heat roller 202, while the middle heat roller 2
A lower fixing unit formed as a second fixing unit formed at a pressure contact portion between the second heat roller 203 and the lower heat roller 203 performs fixing in black and white copying.

Therefore, the surface layer is formed by the upper heat roller 2
01 is formed of silicon rubber, the middle heat roller 202 is formed of Teflon rubber, and the lower heat roller 203 is formed of Teflon rubber or other suitable rubber. The surface of the upper heat roller 201 is a very smooth surface in order to obtain high releasability from the three-layer toner image for obtaining a full-color image.

Each of the heat rollers 201 to 203 has a hollow shape, and a heater lamp 204 for heating is provided in the hollow portion. Each heat roller 201-203
Around the thermistor 20 that detects its surface temperature
5. Thermostat (not shown) incorporated in circuit of heater lamp 204, and heat rollers 201-203
A cleaning roller 206 for removing toner and the like attached to the surface of the printer is provided. Further, around the middle and lower heat rollers 202 and 203, there are provided peeling claws 207 for peeling the paper from the roller surface, while around the upper heat roller 201, there is provided an oil application roller 208 impregnated with silicon oil. Have been.

The oil application roller 208 applies silicone oil to the surface of the upper heat roller 201 to prevent color toner from adhering to the surface of the heat roller, that is, to prevent offset, thereby ensuring the releasability of the color toner image. , For imparting gloss to a full-color copy image. The oil application roller 208 is attached to one end of a roller holder 210 that rotates around a support shaft 219,
Eccentric cam 21 provided at the other end of roller holder 210
The upper fixing unit is pressed against the upper heat roller 201 when the upper fixing unit is used by a mechanism including 1 and a tension spring (not shown).

The upper and lower heat rollers 201 to 2
03 rotates the upper and lower heat rollers 201 and 203
, And the middle heat roller 202 is driven, and the upper and lower heat rollers 201 and 203 are driven by the drive motor 104 shown in FIG. That is, the driving force of the pulley 212, which rotates in the counterclockwise direction by the driving force of the driving motor 104, is applied to the shaft 2 of the lower heat roller 203 via the timing belt 213.
The lower heat roller 203 rotates counterclockwise by being transmitted to the pulley 214 provided in the motor 15. On the other hand, the driving force of the pulley 212 is adjusted by the timing belt 216, the pulley 217, and the gear 21.
8, 219, pulley 220, timing belt 221,
By being transmitted to the pulley 224 provided on the shaft 225 of the upper heat roller 201 via the pulley 222 and the timing belt 223, the upper heat roller 201
Rotates clockwise. Therefore, pulleys 212, 214, 217, 220, 222,
224, gears 218 and 219, and timing belt 2
The heat roller rotation drive mechanism 240 is constituted by 13, 216, 221, 223 and the like.

The middle heat roller 202 has a shaft 235
Through the front and rear fixing frames 228 and 229
, The position in the up-down direction is fixed and provided rotatably. The upper and lower heat rollers 201 and 203 are held by upper and lower roller frames 226 and 227, respectively, as shown in FIGS. The upper and lower roller frames 226 and 227 move up and down about the fulcrum 230 and 231, so that the upper and lower heat rollers 201 and 203 move up and down so as to be separated from and contact with the middle heat roller 202. Section or a lower fixing section. The middle heat roller 202 rotates counterclockwise when it is pressed against the upper heat roller 201 to form an upper fixing portion,
When a lower fixing portion is formed by being pressed against the lower heat roller 203, the lower fixing portion rotates clockwise and rotates forward and reverse according to the fixing portion used.

The above-mentioned suction unit 100 is shown in FIG.
As shown in FIG. 1, the transport belts 101 are supported by a drive shaft 102 on the paper input side and a driven shaft 103 on the paper output side. Then, the driving shaft 102 is rotated by the driving force transmitted from the driving motor 104 via the timing belt 105, so that the transport belt 10 is rotated.
1, 101 moves around in the direction D in the figure. In addition, the driven shaft 103 is mounted on the suction frame 1 movably up and down around the drive shaft 102 side.
06 is rotatably supported at the paper output side end. Note that the sheet transport moving unit 121 is provided with the transport belts 101 and 10.
1. It comprises a vertically moving part such as the suction frame 106.

The driving force from the driving motor 104 is
The signal is transmitted to a shaft 303 with a cam provided below the sheet transporting unit 121 via a timing belt 105, a pulley 306, and a clutch 307. The cam with a cam 303 has a cam 300 for a heat roller and a cam 3 for a suction unit.
01 and 301 are attached two by two in opposite phase. The clutch 307 has a locking projection formed at a position shifted by 180 °, and the latch of the solenoid 304 can be engaged and disengaged with the locking projection. When the latch of the solenoid 304 is disengaged from the locking projection of the clutch 307, the shaft with cam 303 makes a half turn, and when the latch and the locking projection engage, the shaft with cam 30 rotates.
The positions of the cams 300 and 301 fixed to 3 are held.

As shown in FIGS. 4 and 5, one end of the upper and lower roller frames 226 and 227 is fixed to the fixing frames 228 and 229, and the upper and lower roller frames 226 and 227 are respectively connected to the middle heat roller. 20
The tension springs 232 and 233 that draw toward the two sides are attached. The tension springs 232 and 233 maintain the contact state of the heat roller cam 300 when the heat roller cam 300 contacts the upper roller frame 226 or the lower roller frame 227. The upper heat roller 20 held by the roller frame 226 or the lower roller frame 227
1, or the pressure contact state between the lower heat roller 203 and the middle heat roller 202 is maintained. That is, the upper and lower heat rollers 201 and 203 are configured such that the state of separation and contact with the middle heat roller 202 is controlled by rotation of the heat roller cam 300.

A tension spring 108 for urging the suction unit 100 downward is attached to the suction unit 100 so as to maintain the contact state between the suction unit cam 301 and the lower surface of the sheet transporting unit 121. Has become. That is, the suction unit cam 301
However, by rotation, the sheet conveyance moving unit 121
An upper position as a first fixing unit sheet conveying position for conveying the sheet to the upper fixing unit, and a second position for conveying the sheet to the lower fixing unit.
The fixing unit is moved to a lower position as a sheet transport position.

The timing belt 105, pulley 306, clutch 307, solenoid 3 shown in FIG.
04, cam shaft 303 (rotating member) , heat roller cam 300 (first cam) , suction unit cam 301 (second cam) , upper roller frame 226 (first
Support member), lower roller frame 227 (second support portion)
), The tension springs 108, 232, 233, etc., constitute a moving mechanism as moving means for simultaneously moving the upper and lower heat rollers 201, 203 and the sheet conveying moving unit 121.

In the above configuration, when the copy start button is turned on after the full color copy selection key is turned on, the drive motor 104 is driven under the control of a control device (not shown). When performing a full color copy,
The maximum eccentric portion of the heat roller cam 300 comes into contact with the lower roller frame 227, and as shown in FIG.
The lower heat roller 203 is separated from the middle heat roller 202, and the upper heat roller 201 is pressed against the middle heat roller 202 by the urging force of the tension spring 232 to form an upper fixing portion. At this time, the maximum eccentric portion of the suction unit cam 301 comes into contact with the lower surface of the sheet conveyance moving unit 121, and the sheet conveyance moving unit 121 is held at the upper position.

Then, the driving force of the drive motor 104 shown in FIG. 1 is transmitted to the shaft 225 of the upper heat roller 201 via the heat roller rotation drive mechanism 240, so that the upper heat roller 201 rotates clockwise. After rotation, the middle heat roller 202 rotates counterclockwise following the rotation of the upper heat roller 201. The driving force of the driving motor 104 is the timing belt 105, the pulley 2
Drive shaft 102 of suction unit 100 through 34
, And the conveyor belts 101 circulate in the direction D in the figure. The oil application roller 2 shown in FIG.
08 is pressed against the upper heat roller 201.

The full-color copy mode has a copy cycle in which yellow, magenta, and cyan are developed and transferred to the transfer belt 17 shown in FIG. 2, respectively. When the operation is completed, first, a yellow copy cycle is executed.

First, the surface of the photoconductor 8 rotating in the B direction is uniformly charged by the charging charger 9, and the first scanning of the original on the original table 3 is performed by the exposure optical system 4. Light reflected from the original is exposed to the surface of the photoconductor 8 between the charging charger 9 and the inter-image eraser (not shown) via a blue color separation filter (not shown) and a slit (not shown). The point is irradiated to expose the photoreceptor 8 to form an electrostatic latent image. Next, the potential of the non-image area on the photoreceptor 8 is removed by an inter-image eraser.
1 to form a yellow toner image.
Next, the yellow toner image on the surface of the photoreceptor 8 is transferred to the transfer belt 17 moving in the C direction by the first transfer roller 21 to which a negative high voltage is applied. The residual toner on the surface of the photoconductor 8 is removed by the cleaning device 15, and the residual potential on the surface of the photoconductor 8 is removed by the charge removing device 16.

When the above-described series of operations is completed, the photosensitive member 8 is charged again by the charging charger 9, and the original is scanned by the exposure optical system 4 for the second time. In this case, a green color separation filter is used, and the electrostatic latent image formed on the photoconductor 8 is developed with magenta toner in the magenta developing tank 12. The magenta toner image formed on the surface of the photoconductor 8 is transferred by the first transfer roller 21 so as to be superimposed on the previous yellow toner image on the transfer belt 17. Thereafter, similarly, the third scanning by the exposure optical system unit 4 using the red color separation filter is performed, and the cyan toner image is developed on the photoconductor 8 by the development with the cyan toner in the cyan developing tank 13. It is formed. This cyan toner image is transferred onto the magenta toner image on the transfer belt 17.

Next, the second transfer roller 22, which has been separated from the transfer belt 17 in the operation so far, is
7, and a negative voltage higher than the surface potential of the transfer belt 17 is applied to the second transfer roller 22, so that the second transfer roller 22 is conveyed from the sheet cassette 25 or the sheet tray 26 via the registration roller 24. The three-layer toner image on the transfer belt 17 is transferred to the paper.

The above-described paper on which the toner image has been transferred is formed on the upper heat roller 201 and the middle heat roller 202 by the conveyance belts 101 of the suction unit 100 arranged at the upper position. Transported to the department. In the upper fixing section, the three-layer color toner image on the paper is heated and melted by the upper and middle heat rollers 201 and 202, and is fixed on the paper. At this time,
Since silicon oil is supplied to the upper heat roller 201 from the oil application roller 208, offset of the toner image to the upper heat roller 201 is prevented, and gloss is imparted to the full-color toner image on the sheet.
The paper discharged from the fixing device 200 is supplied to the discharge rollers 30.
Is discharged onto the discharge tray 31.

Next, the black-and-white copying operation of the copying machine will be described. When the copy start button is turned on after the black-and-white copy selection key (not shown) is turned on from the state where the full-color copy is possible, the latch of the solenoid 304 shown in FIG.
07, the cam-equipped shaft 303 rotates by 180 ° by the driving force of the driving motor 104 transmitted via the timing belt 105 and the pulley 306, as shown in FIG. The maximum eccentric portion of the cam 300 contacts the upper roller frame 226, and the minimum eccentric portion of the suction unit cam 301 contacts the lower surface of the sheet conveyance moving unit 121. That is, the lower heat roller 203 presses against the middle heat roller 202 by the urging force of the tension spring 233 to form a lower fixing portion, and the upper heat roller 201
And the sheet conveying / moving unit 121 moves to a lower position. The engagement of the latch of the solenoid 304 shown in FIG.
The positional relationship between 203 and the sheet conveying / moving unit 121 is maintained.

Further, the driving force of the driving motor 104 is transmitted through the heat roller rotation driving mechanism 240, and the lower heat roller 203 rotates counterclockwise, and accordingly, the middle heat roller 202 rotates clockwise. Rotate in the direction.
Conveyor belts 101 of suction unit 100
Moves around in the direction D in the drawing, as in full-color copying. During black and white copying, the oil application roller 208 shown in FIG.

After the operations of the fixing device 200 and the suction unit 100 as described above are completed, the surface of the photoconductor 8 shown in FIG. 3 is scanned. The reflected light from the document is guided to the exposure optical system 4 and irradiated on the photoconductor 8 without passing through the color separation filter and the slit, and an electrostatic latent image is formed on the photoconductor 8. Thereafter, the above-described electrostatic latent image is developed by the black developing tank 10, and the black toner image thus formed is transferred to the transfer belt 17 and further transferred to paper.

The above-described paper on which the toner image has been transferred is transferred to the lower fixing portion formed at the pressure contact portion between the middle heat roller 202 and the lower heat roller 203 by the conveyor belts 101 of the suction unit 100 arranged at the lower position. And the toner image is fixed on the paper. Thereafter, the sheet discharged from the fixing device 200 is discharged onto a discharge tray 31 by a discharge roller 30.

As described above, in the copying machine of the present embodiment, the rotation of the upper and lower heat rollers 201 and 203 and the conveyance belt 101 and
Circular movement of 101, upper and lower heat rollers 201.2
03, and the sheet conveyance moving unit 121 is moved up and down. Further, the upper and lower heat rollers 201
The up and down movement of 203 and the up and down movement of the sheet conveyance moving unit 121 are performed by the same moving mechanism, and compared with the case where these are individually driven, the moving mechanism, the sensor, etc. , The number of parts can be reduced, and the cost can be reduced. Further, the upper and lower heat rollers 201 and 203 and the sheet conveying / moving unit 121
Is always linked, there is no need to control the timing of the movement of the two, and it is possible to avoid the possibility that the positional relationship between the two may not match due to the occurrence of a malfunction. Occurrence is reduced.

[0043]

As described above, the electrophotographic apparatus of the present invention rotatably supports the first fixing roller and forms the second fixing roller.
Direction and separation of the first fixing roller against the roller
A first support member movable in a direction to be
Roller is rotatably supported, and the third fixing roller is fixed to the second fixing roller.
Move in the direction of pressing and separating the application roller
A possible second support member, a rotatable rotating member,
Is provided on the rotating member of the
A first cam for moving the first and second support members;
The rotating member is provided on the rotating member.
Mover having a second cam for moving the sheet transport moving section
A step, and the moving means moves with the rotation of the rotating member.
By the first and second cam rotating Te, the first fixing roller is pressed against the second fixing roller, and the third fixing roller with it is separated from the second fixing roller, the Sea <br/> preparative conveying movement Unit to the first fixing unit sheet transport position
A first state, to move the third fixing roller is pressed against the second fixing roller, and the first fixing roller with is separated from the second fixing roller, the sheet transport moving portion to the second fixing portion sheet transport position This is a configuration for forming the second state .

Therefore, the number of parts such as the moving mechanism and the sensor can be reduced as compared with the case where the first and third fixing rollers and the sheet conveying moving unit are driven by different moving mechanisms, respectively. The cost can be reduced, and there is no need to control the timing for moving the first and third fixing rollers and the sheet conveying moving unit,
Since it is possible to avoid a possibility that a malfunction such as a positional relationship does not occur, a paper jam can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a fixing device and a suction unit in a copying machine according to an embodiment of the present invention.

FIG. 2 is an overall configuration diagram showing the copying machine.

FIG. 3 is an enlarged view of a main part showing an internal structure of the fixing device.

FIG. 4 is a schematic front view showing a positional relationship between the fixing device and the suction unit during full-color copying.

FIG. 5 is a schematic front view showing a positional relationship at the time of monochrome copying in the configuration shown in FIG. 4;

FIG. 6 is a perspective view of a suction unit provided in a conventional copying machine.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 suction unit (sheet conveying device) 105 timing belt (moving means) 121 sheet conveying moving unit 200 fixing device 201 upper heat roller (first fixing roller) 202 middle heat roller (second fixing roller) 203 lower heat roller (third) Fixing roller) 300 Heat roller cam (moving means) 301 Suction unit cam (moving means) 303 Shaft with cam (moving means) 304 Solenoid (moving means) 306 Pulley (moving means) 307 Clutch (moving means)

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Yasunori Kawai 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (56) References JP-A-51-98036 (JP, A) JP-A-2 -126271 (JP, A) Japanese Utility Model Showa 60-159463 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 13/20 G03G 15/20

Claims (1)

(57) [Claims] A first fixing roller provided between the first fixing roller and the second fixing roller;
A fixing device in which a fixing portion is formed, and a second fixing portion is formed in a pressure contact portion between the second fixing roller and the third fixing roller, and the sheet conveyed to each fixing portion is fed in a discharge direction by rotation of the fixing roller. And a sheet transport moving unit movably provided at a first fixing unit sheet transport position for transporting the sheet on which the toner image has been transferred to the first fixing unit and a second fixing unit sheet transport position for transporting the sheet to the second fixing unit. An electrophotographic apparatus comprising: a sheet conveying device having a first fixing roller rotatably supported by a second fixing roller;
The first fixing roller in the direction of pressure contact and the
And a third fixing roller rotatably supported in a first fixing member movable in a direction
The third fixing roller in the direction in which it comes into pressure contact with
A second supporting member movable in a direction, a rotating member driven to rotate, and a rotating member provided on the rotating member.
A first cam that moves the first and second support members, and a first cam that is provided on the rotating member and that rotates with the rotation of the rotating member.
A second cam for moving the sheet transporting section.
Moving means, which rotates with the rotation of the rotating member.
By the first and second cams, the first fixing roller is pressed against the second fixing roller, and the third fixing roller second
Together it is separated from the fixing roller, a first state for moving the sheet conveyance moving unit to the first fixing portion sheet transport position
When, moving the third fixing roller is pressed against the second fixing roller, and the <br/> first fixing roller with is separated from the second fixing roller, the sheet transport moving portion to the second fixing portion sheet transport position An electrophotographic apparatus for forming a second state .